366 ELEMENTARY BIOLOGY. [CHAP. 



and the rolled-in peristome. In this space the 

 cilia can frequently be seen moving, 

 y. Structure ; as in i . a. c- 

 b. The stalk ; thrown into corkscrew-like folds. 



3. The movements of Vorticella. 



a. The ciliary movement. 



a. Examine the cilia carefully ; delicate homo- 

 geneous processes; their length, diameter and 

 form ; their position. 



y8. The continuity of the cilia with the cortical 

 layer. 



y. The function of the cilia; their rapid move- 

 ments, alternately bending and straightening : 

 the co-ordination of these movements; they 

 work in a definite order; note the currents 

 produced in the neighbouring water (if neces- 

 sary introduce a few particles of carmine under 

 the coverslip) ; the sweeping of small bodies 

 down the gullet. 



b. The movements of the contractile vesicle. Tolerably 

 regular rhythmic distension and collapse (diastole 

 and systole). 



c. The currents in the endosarc carrying round the in- 

 gested bodies. 



d. The movements of the animal as a whole. (Ex- 

 amine under \ inch or \ inch obj.) 



a. Its extreme irritability ; it contracts on the 

 slightest stimulation, often without any appa- 

 rent cause. 



ft. The movements which occur in contraction; 



